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Bluetooth Presentation by Anna La Mura and Marcus Nagel TIM01AGR.

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Presentation on theme: "Bluetooth Presentation by Anna La Mura and Marcus Nagel TIM01AGR."— Presentation transcript:

1 Bluetooth Presentation by Anna La Mura and Marcus Nagel TIM01AGR

2 Overview Bluetooth History Bluetooth Basics Application Areas Protocols Networks Specification Documents Basic Technology Error Correction Security

3 Bluetooth and its Name King Harald Bluetooth (A.D. 940 to 985) 10th. Century Viking king in Denmark Credited for uniting the country and established Christianity Viking staates included Norway & Sweden, which gives the connection to Ericsson

4 Bluetooth and its development Ericsson Mobile Communication Bluetooth Special Interest Group (SIG) 5 founding members Ericsson, Nokia, IBM, Intel & Toshiba Promoters Group SIG founders plus 3COM, Lucent, Microsoft, Motorola Now over 1900 members

5 Overview Universal short-range wireless capability Uses 2.4-GHz band Available globally for unlicensed users Devices within 10 m can share up to 720 kbps of capacity Supports open-ended list of applications Data, audio, graphics, video

6 Bluetooth Application Areas Data and voice access points Real-time voice and data transmissions Cable replacement Eliminates need for numerous cable attachments for connection Ad hoc networking Device with Bluetooth radio can establish connection with another when in range

7 Bluetooth Standards Documents Core specifications Details of various layers of Bluetooth protocol architecture Profile specifications Use of Bluetooth technology to support various applications

8 Protocol Architecture Bluetooth is a layered protocol architecture Core protocols Cable replacement and telephony control protocols Adopted protocols Core protocols Radio Baseband Link manager protocol (LMP) Logical link control and adaptation protocol (L2CAP) Service discovery protocol (SDP)

9 Protocol Architecture Cable replacement protocol RFCOMM Telephony control protocol Telephony control specification – binary (TCS BIN) Adopted protocols PPP TCP/UDP/IP OBEX WAE/WAP

10 Usage Models File transfer Internet bridge LAN access Synchronization Three-in-one phone Headset

11 Piconets and Scatternets Piconet Basic unit of Bluetooth networking Master and one to seven slave devices Master determines channel and phase Scatternet Device in one piconet may exist as master or slave in another piconet Allows many devices to share same area Makes efficient use of bandwidth

12 Piconet Master controls entire piconet Maximum devices in a piconet: 1 master 7 active slaves 255 standby slaves Device can participate in more than 1 piconet Master Online Slave Standby Slave

13 A group of piconets with overlapping areas of coverage Each piconet is identified by different frequency hopping sequence Slave to 1 piconet can be master to another A device can only be Master to a single piconet Scatternet Master Active Slave Standby Parked Slave

14 Wireless Network Configurations

15 Radio Specification Classes of transmitters Class 1: Outputs 100 mW for maximum range Power control mandatory Provides greatest distance Class 2: Outputs 2.4 mW at maximum Power control optional Class 3: Nominal output is 1 mW Lowest power

16 Frequency Hopping in Bluetooth Provides resistance to interference and multipath effects Provides a form of multiple access among co- located devices in different piconets

17 Frequency Hopping Total bandwidth divided into 1MHz physical channels FH occurs by jumping from one channel to another in pseudorandom sequence Hopping sequence shared with all devices on piconet Piconet access: Bluetooth devices use time division duplex (TDD) Access technique is TDMA FH-TDD-TDMA

18 Frequency Hopping

19 Physical Links between Master and Slave Synchronous connection oriented (SCO) Allocates fixed bandwidth between point-to-point connection of master and slave Master maintains link using reserved slots Master can support three simultaneous links Asynchronous connectionless (ACL) Point-to-multipoint link between master and all slaves Only single ACL link can exist

20 Bluetooth Packet Fields Access code – used for timing synchronization, offset compensation, paging, and inquiry Header – used to identify packet type and carry protocol control information Payload – contains user voice or data and payload header, if present 72b 54b 0 – 2745b Acess code Packet header Payload

21 Types of Access Codes Channel access code (CAC) – identifies a piconet Device access code (DAC) – used for paging and subsequent responses Inquiry access code (IAC) – used for inquiry purposes

22 Access Code Preamble – used for DC compensation 0101 if LSB of sync word is if LSB of synch word is 1 Sync word – 64-bits, derived from: 7-bit Barker sequence Lower address part (LAP) Pseudonoise (PN) sequence Trailer 0101 if MSB of sync word is if MSB of sync word is 0

23 Packet Header Fields AM_ADDR – contains active mode address of one of the slaves Type – identifies type of packet Flow – 1-bit flow control ARQN – 1-bit acknowledgment SEQN – 1-bit sequential numbering schemes Header error control (HEC) – 8-bit error detection code

24 Payload Format Payload header L_CH field – identifies logical channel Flow field – used to control flow at L2CAP level Length field – number of bytes of data Payload body – contains user data CRC – 16-bit CRC code

25 Error Correction Schemes 1/3 rate FEC (forward error correction) Used on 18-bit packet header 2/3 rate FEC Used in DM packets, data fields of DV packet, FHS packet ARQ Used with DM and DH packets

26 ARQ Scheme Elements Error detection – destination detects errors, discards packets Positive acknowledgment – destination returns positive acknowledgment Retransmission after timeout – source retransmits if packet unacknowledged Negative acknowledgment and retransmission – destination returns negative acknowledgement for packets with errors, source retransmits

27 Logical Channels Link control (LC) Link manager (LM) User asynchronous (UA) User isochronous (UI) Use synchronous (US)

28 Channel Control States of operation of a piconet during link establishment and maintenance Major states Standby – default state Connection – device connected

29 Channel Control Interim substates for adding new slaves Page – device issued a page (used by master) Page scan – device is listening for a page Master response – master receives a page response from slave Slave response – slave responds to a page from master Inquiry – device has issued an inquiry for identity of devices within range Inquiry scan – device is listening for an inquiry Inquiry response – device receives an inquiry response

30 State Transition Diagram

31 Inquiry Procedure Potential master identifies devices in range that wish to participate Transmits ID packet with inquiry access code (IAC) Occurs in Inquiry state Device receives inquiry Enter Inquiry Response state Returns FHS packet with address and timing information Moves to page scan state

32 Page Procedure Master uses devices address to calculate a page frequency-hopping sequence Master pages with ID packet and device access code (DAC) of specific slave Slave responds with DAC ID packet Master responds with its FHS packet Slave confirms receipt with DAC ID Slaves moves to Connection state

33 Slave Connection State Modes Active – participates in piconet Listens, transmits and receives packets Sniff – only listens on specified slots Hold – does not support ACL packets Reduced power status May still participate in SCO exchanges Park – does not participate on piconet Still retained as part of piconet

34 Bluetooth Audio Voice encoding schemes: Pulse code modulation (PCM) Continuously variable slope delta (CVSD) modulation Choice of scheme made by link manager Negotiates most appropriate scheme for application

35 Bluetooth Link Security Elements: Authentication – verify claimed identity Encryption – privacy Key management and usage Security algorithm parameters: Unit address Secret authentication key Secret privacy key Random number

36 LMP PDUs General response Security Service Authentication Pairing Change link key Change current link key Encryption

37 LMP PDUs Time/synchronization Clock offset request Slot offset information Timing accuracy information request Station capability LMP version Supported features

38 LMP PDUs Mode control Switch master/slave role Name request Detach Hold mode Sniff mode Park mode Power control

39 LMP PDUs Mode control (cont.) Channel quality-driven change between DM and DH Quality of service Control of multislot packets Paging scheme Link supervision

40 L2CAP Provides a link-layer protocol between entities with a number of services Relies on lower layer for flow and error control Makes use of ACL links, does not support SCO links Provides two alternative services to upper-layer protocols Connection service Connection-mode service

41 L2CAP Logical Channels Connectionless Supports connectionless service Each channel is unidirectional Used from master to multiple slaves Connection-oriented Supports connection-oriented service Each channel is bidirectional Signaling Provides for exchange of signaling messages between L2CAP entities

42 L2CAP Packet Fields for Connectionless Service Length – length of information payload, PSM fields Channel ID – 2, indicating connectionless channel Protocol/service multiplexer (PSM) – identifies higher- layer recipient for payload Not included in connection-oriented packets Information payload – higher-layer user data

43 Signaling Packet Payload Consists of one or more L2CAP commands, each with four fields Code – identifies type of command Identifier – used to match request with reply Length – length of data field for this command Data – additional data for command, if necessary

44 L2CAP Signaling Command Codes

45 L2CAP Signaling Commands Command reject command Sent to reject any command Connection commands Used to establish new connections Configure commands Used to establish a logical link transmission contract between two L2CAP entities

46 L2CAP Signaling Commands Disconnection commands Used to terminate logical channel Echo commands Used to solicit response from remote L2CAP entity Information commands Used to solicit implementation-specific information from remote L2CAP entity

47 Flow Specification Parameters Service type Token rate (bytes/second) Token bucket size (bytes) Peak bandwidth (bytes/second) Latency (microseconds) Delay variation (microseconds)

48 Thank you for your attention ???????????? If you have any Questions feel free to ask !!! ????????????


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